CANNeCTIN Knowledge Translation Project

Researchers from the CANNeCTIN KT Working Group - Robby Nieuwlaat, Brian Haynes, John Eikelboom, Jack Tu, Jafna Cox, and Stuart Connolly - are undertaking the following KT study in 900 patients from 45 family practices across the country to evaluate whether or not family physicians can improve the quality of INR control by using a simple warfarin maintenance dosing algorithm, in either paper or web-based form.

Cluster randomized trial of a simple warfarin maintenance dose algorithm on the quality of INR control among family practices

Poor INR control in atrial fibrillation patients on warfarin is common in Canadian clinical practice and is associated with adverse clinical outcomes. To have optimal benefit of warfarin, the 2008 guidelines for the management of vitamin K antagonists by the American College of Chest Physicians recommend management of warfarin dosing in a standardized way. Several evidence-based methods are available to achieve this: anticoagulation clinic, computerized dosing support and patient self-management. According to a survey in the Hamilton area, half of family physicians do not use an evidence-based method for warfarin dosing in atrial fibrillation patients. Current evidence-based warfarin dosing methods are either expensive, complex or have limited availability. A simple and cheap manual dosing algorithm might provide similar dosing quality as current methods, but there is scarce research evidence for this. We have good preliminary data that the use of a very simple warfarin maintenance dosing algorithm improves INR control. Adherence to this algorithm correlated with improved INR control in a large clinical trial (RE-LY). In addition, local implementation of this algorithm resulted in an increased mean time-in-therapeutic-range for INR values from 65% to 72% in a before-after study. We will test in a cluster randomized trial whether family physicians, who currently use no evidence based warfarin dosing method, can improve the quality of INR control by using this simple warfarin maintenance dosing algorithm, in either a paper or web-based form.